Conventionally, paper is widely used as a medium on which information such as images and characters is recorded. The use of paper as information recording medium leads to advantages as follows; information recorded can be viewed all together at once; a plurality of sheets of paper carrying information thereon can be placed side by side so that the information thereon are glanced; and a great degree of freedom is allowed regarding, for example, a place to view the information. The sheets of paper on which information is recorded, however, are disposed upon update of information since rewriting of information thereon is bothersome. This causes exhaustion of resources such as timber resources which are raw materials of paper, as well as an increase in discharge of carbon dioxide, thereby leading to an increase in environmental loads.
Further, CRT display devices and liquid crystal display devices may be cited as examples of information display means for displaying information such as images and characters. Since information displayed on such display devices is easily rewritten or erased, the display devices have an advantage that rewriting of information can be performed repeatedly. The CRT display devices, however, have an drawback in that working on the CRT display devices tire eyes of the users, while the liquid crystal display devices have insufficient resolution, as compared with the resolution in the case where information is recorded on paper.
Therefore, recording media which possess advantages of paper and on which image information is rewritten repeatedly, as is on a display device, have been sought for. An example of an image recording device for use with such a recording medium on which image information is rewritable is disclosed by the Japanese Publication for Laid-Open Patent Application No. 67141/1994 (Tokukaihei 6-67141 (date of publication: Mar. 11, 1994)).
With the image recording device disclosed by the foregoing publication, a recording medium sheet arranged as follows is used: organic or inorganic protective films are provided on surfaces of both sides of such an optical modulation member as a compound film made of a high-molecular material and a low-molecular liquid crystal or a compound film made of a high-molecular liquid crystal and a low-molecular liquid crystal. In other words, the foregoing image recording device performs the writing and erasure of information with respect to the foregoing recording medium sheet by changing an alignment state of liquid crystal of the recording medium sheet by application of an electric field thereto.
Here, the following description will explain a process of the writing and erasure of information performed by the foregoing image recording device, while referring to FIG. 45.
First, initialization of a recording medium sheet 501 is carried out as follows. The recording medium sheet 501 is caused to go through between two rolls 512a and 512b which are connected to an initialization power source. Here, a high frequency voltage, or alternatively, a charge or voltage which has a polarity opposite to that of a charge or voltage with that image information is written in the recording medium sheet 501, is applied to the recording medium sheet 501, whereby the information is erased and initialization is achieved.
Thereafter, the recording medium sheet 501 is caused to go through between a drum 502 and a transfer roller 506 so that an electric charge or voltage pattern is applied to the recording medium sheet 501. With this, information is written therein. Prior to that, a surface of an organic photosensitive body 503 of the drum 502 has been kept in a state of being charged with negative electric charges by use of a corona charger 505, while light of a pattern corresponding to character or image information has been projected by a light projecting unit 504 to the same surface, so that an electric charge pattern corresponding to the character or image information is preparatorily formed thereon.
Then, for elimination of electric shocks, the recording medium sheet 501 in which the information is written is caused to go through between two discharge-use rolls 508a and 508b so that electric charges are removed, and thereafter, the recording medium sheet 501 is ejected.
The recording medium sheet 501 is formed in a film form with a thickness of about 0.1 mm, made of a plastic, and arranged so that information such as characters and images is rewritten and erased repeatedly as well as that an optical modulation member constituting the recording medium sheet 501 has a property as a memory thereby being capable of storing information written therein for a long time.
As described above, the information recording by using the conventional recording medium sheet 501 is characterized by maintaining advantages of paper while being capable of repeatedly rewriting image information as is the case with the display devices.
Regarding the foregoing recording medium sheet, however, its size is limited, depending on a size of an image recording device. In the case where much information is recorded, therefore, a plurality of recording medium sheets are needed. More specifically, to view volumes of information, it is necessary to compile the recording medium sheets all together, since information such as characters or images is individually recorded on each recording medium sheet. Therefore, what is obtained as a result of compilation is very bulky as reference, with no difference from a conventional book.
Moreover, since the foregoing recording medium sheet is made of a plastic sheet as a component thereof, such reference composed of a plurality of the recording medium sheets becomes heavier than paper one, and inconvenient for carrying.
Besides, whenever information recorded on the recording medium sheet is to be rewritten, access to an image recording device such as a copying machine or a printer is required, resulting in an inconvenience that information cannot be recorded at any desired place.
Furthermore, the Japanese Publication for Laid-Open Patent Application No. 48604/1998 (Tokukaihei 10-48604 (date of publication: Feb. 20, 1998)) discloses an advertisement-use medium in which information is repeatedly rewritten. The advertisement-use medium is made of a liquid crystal/polymer compound film with dispersed smectic liquid crystal in a polymer matrix, and erasure and rewriting of information recorded therein is carried out by application of heat or an electric field to the compound film. According to the foregoing publication, the advertisement-use medium may be used as an advertisement-use panel. placed at a desired position in a train, a bus, or the like.
To change the advertisement, the foregoing advertisement-use medium is wound and taken into a winding device, while information recorded on the advertisement-use medium is erased by use of an erasing unit provided beside the winding device. Then, the winding device is displaced, and a writing unit provided beside the winding device is connected to an information source, so that character information is obtained from the information source. Thereafter, the advertisement-use medium is pulled out of the winding device, while the information is outputted from the writing unit to the advertisement-use medium. The winding device in a state in which the advertisement-use medium is pulled out therefrom is fitted at a predetermined display position in a train, a bus, or the like, so that the advertisement is displayed.
Thus, there have been drawbacks in that it is necessary to displace the entire winding device, to change the advertisement, i.e., to rewrite information, and besides, that new information to be recorded is obtained only at a place where an information source is located.